feat: Apply PreferredURLPatterns to Configuration refresh server list

The RefresherBase now respects the PreferredURLPatterns option when
randomizing server lists, ensuring preferred servers are tried first
while maintaining randomization within each priority group.

Author: chrisburr

src/DIRAC/ConfigurationSystem/private/RefresherBase.py

@@ -1,7 +1,7 @@
 import time
 
 from DIRAC.ConfigurationSystem.Client.ConfigurationData import gConfigurationData
-from DIRAC.ConfigurationSystem.Client.PathFinder import getGatewayURLs
+from DIRAC.ConfigurationSystem.Client.PathFinder import getGatewayURLs, groupURLsByPriority
 from DIRAC.Core.Utilities import List
 from DIRAC.Core.Utilities.EventDispatcher import gEventDispatcher
 from DIRAC.Core.Utilities.ReturnValues import S_ERROR, S_OK
@@ -138,7 +138,9 @@ def _refresh(self, fromMaster=False):
         if not initialServerList:
             return S_OK()
 
-        randomServerList = List.randomize(initialServerList)
+        randomServerList = []
+        for urlGroup in groupURLsByPriority(initialServerList):
+            randomServerList.extend(List.randomize(urlGroup))
         gLogger.debug(f"Randomized server list is {', '.join(randomServerList)}")
 
         for sServer in randomServerList: